Turn Character Into a Sketch
The Compositing Method

First, you could go for a cartoon render of your model. This effect uses advanced Compositing with the goal of creating a comic style look. You can read about it here. It can create results like this...



...but you'll have to deal with stuff like this.



OpenGL

There is a way to render in Blender that uses grease-pencil. You can look into it here.